Type wheel setting and re-setting means in selective bed and platen printing machines

ABSTRACT

A high speed printing apparatus in which a plurality of type wheels each having a helical spring disposed therein are rotatably mounted on a shaft in side-by-side relation, with one end of the helical spring anchored to the type wheel and the other end thereof anchored to an operation bar to bias the type wheel in one direction, and the type wheels are rotated all at once by rotating the operation bar and stopped by respective associated selection members when the type faces to be printed of the respective type wheels are located in the printing position.

United States Patent Nihira et al. I I

[ Sept. 12, 1972 [54] TYPEWHEEL SETTING AND RE- SETTING MEANS IN SELECTIVE BED AND PLATEN PRINTING MACHINES [72] Inventors: Shohachi Nihira, Tokyo; Yasuo Okawara; Takehisa Naito, both of Hoya; Mikio Moriya, Tokorozawa,

all of Japan .[73] Assignee: Citizen Watch Co., Ltd., Shinjuku-ku, Tokyo, Japan 22 Filed: April 24, 1970 211 Appl.No.: 31,494

52 U.S.Cl ..101/95 51] Int. (31.. ...B4lj 1/48 58 Field of Search ..101/93 0, 93 R, 93 MM, 95,

[56] Retell- 11665 Cited v UNITED STATES PATENTS 2,576,041 11/1951 Pitts... ..-......10l/99 2,766,687 10/1956 'Williams ..10l/1l0x 3,139,819 7/1964 Hilpert 101/93 3,269,510 8/1966 Peters ..l97/53 3,307,676 3/1967 vHickerson ..197/49 X 3,422,754 1/1969 Bakardjieu et al ..l0l/79 Primary Examinem-William B. Penn Attorney-William D. Hall, Elliott I. Pollock, Fred C. Philpitt, George Vande Sande, Charles F. Steininger and Robert R. Priddy [57] ABSTRACT A high speed printing apparatus in which a plurality of type wheels each having a helical spring disposed therein are rotatably mounted on a shaft in side-byside relation, with one end of the helical spring anchored to the type wheel and the other end thereof anchored to an operation bar to bias the type wheel in one direction, and the type wheels are rotated all at onc'ejby rotating theoperation bar and stopped by respective associated selection members when the type faces to be printed of the respective type wheels are located in the printing position.

6 Claims, 11 Drawing Figures TYPE WHEEL SETTING AND RE-SETTIN G MEANS IN SELECTIVE-BED AND PLATEN PRINTING MACHINES BACKGROUND OF THE INVENTION The present invention relates generally to a printing apparatus and particularly to a printing apparatus by which data, obtained by the operation of an electronic computer, is recorded at a high speed.

Printing apparatus of the type in which a plurality of type wheels, arrangedside-by-side and each having type faces over the peripheral surfaces thereof, are rotated-and stopped individually upon detecting the amounts of rotation of the respective type wheels to locate the type faces to be printed of the type wheels at a printing position, and held stationary in their positions for printing, have been known. These prior art printingapparatus are classified into a first type, in which the type wheels are rotationally driven by a friction clutch, and a second'type in which the type wheels are rotationally driven by a rack in engagement ih wnh.

Printing apparatuses of the first type have the. disadvantage that the mechanism becomescomplicated because each type wheel has the friction clutch accominodated therein. Moreover, since each type wheel is driven by the friction clutch, the, operation is unstable due 'to fluctuation ofthe frictional force and the apparatus is not sufficientlydurable for use over a prolonged period.

Printing apparatuses of the second type, on the other hand, have the disadvantage that alignment of the printed numbers is poor because the positions of the typefaces to beprinted of the respective type wheels are varied by a back-lash between the type wheel and the engaging'rack or sector gear.-They have another disadvantage that the rack-or sector gear makes the type wheel driving mechanism large in size and, there- .fore, the moment of inertia becomes large, making a high speed printing impossible. Further, in these prior art printing apparatuses the selection of type faces and return movement of the type wheel are effected by a reciprocal motion of the type wheel or by two revolutions of the type wheel.

- In printing numbers by a printing apparatus, zeros in the digit positions higher than the highest digit position of the number to be printed are not needed, and further the zero in the next higher digit position relative to the decimal point must be printed where there are no significant figures in the higher digit positions from the decimal point.

In order to discriminate between the unnecessary zeros and the significant zeros mechanically, it has been customary to provide in a printing apparatus discrimination members which engage respective selection members in three different positions, i.e. in a position to discriminate the decimal point, a position to discriminate numbers 1 9 and a position to discriminate zero, into which each of said discrimination members is shifted by a cam having three lobes.

According to this approach discrimination of the decimal point must be effected prior to selection of numbers or, in other words, the discrimination of numbers must be performed after the decimal point has been discriminated. Such an approach, therefore, is defective in that the mechanism becomes complicated into three positions from one another, and that freedom of design is subjected to a limination because the decimal point must be discriminated first.

Another type of printing apparatus has been used in which each type wheel is provided with a decimal point in addition to number type faces so that a decimal point may be printed in any digit position as required. This type of printing apparatus, however, has the disadvantage that it is inevitable forthe zero discriminating mechanism to become complicated, in order to make it possible to print a decimal point in any selected digit position. The small-sized printing apparatuses presently being used in electronic desk computers are predominantly of the type wherein the positions of decimal point are designated, for example, in O, 3, 6 and 9 digit positions, and a printing apparatus of the designated decimal point type wherein the discrimination of zeros SUMMARY THE INVENTION The primary object'of the present invention is to pro- I vide a printing apparatus which is free of the abovedescribed disadvantages and which is small in size and simple in construction.

Another object of the invention is to provide a type wheel-type printing apparatus which is capable of high speed, accurate printing operation.

Still another object of the invention is to provide a small-sized, light-weight printing apparatus in which the positional accuracy of the printed figures is enhanced by directly controlling type wheels by means of a helical spring disposed in each of said type wheels, without using any other intermediate parts.

Still another object of the invention is to provide a printing apparatus in which the selection of figures and the return movement of each type wheel are accomplished successively by one continuous revolution in one direction of said type wheel caused by a helical spring disposed in the type wheel, and the printing speed is thus further increased.

Still another object of the invention is to provide a printing apparatus in which the positions of selection members are discriminated only at the time of selecting a decimal point, and printing of unnecessary zeros is thus avoided.

A further object of the invention is to provide a printing apparatus in which type wheels each having decimal point only and selection members for said type wheels are provided so as to avoid printing of unnecessary zeros.

An additional object of the invention is to provide a printing apparatus in which selection members can be operated by a light force of an electromagnet after said selection member is shifted to a position in the vicinity of the critical point of a reversion spring or a snap spring.

BRIEF DESCRIPTlON OF THE DRAWINGS The present invention will be described in detail FIGS. 2 through 8 are views showing an embodiment of the present invention, in which FIG. 2 is a perspective view showing the appearance of the high speed printing apparatus;

FIG. 3 is a front elevational view of the type selecting portion of FIG. 2;

FIG. 4a is a perspective view of the type selecting portion;

FIG. 4b is a perspective view showing another form of the type wheel buffer mechanism and the platen mounting and demounting mechanism;

FIG. 5 is a front elevational view of the unnecessary zero eliminating mechanism portion of FIG. 2;

FIG. 6 is a perspective view of the unnecessary zero eliminating mechanism of FIG. 2;

FIG. 7 is a front elevational view of another form of the unnecessary zero eliminating mechanism in the high speed printing apparatus;

FIG. 8 is a perspective view of the unnecessary zero eliminating mechanism of FIG. 7;

FIG. 9 is a perspective view, partially in cross-section, of the essential portion of the ribbon feeding mechanism; and

FIG. 10 is a perspective view of the essential portion of the paper feeding mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 11 designates a type wheel provided with a plurality of type faces for numerals 0 9, a decimal point, and a blank 10 on the peripheral surface thereof at equal intervals, and with a pinion 13 on one side thereof. A plurality of such type wheels are rotatably mounted on a shaft 12 in parallel side-by-side relation in a number corresponding to the number of required decimal digit positions in a horizontal direction.

Reference numeral 14 designates a sector to rotationally drive the type wheel 11 to bring a desired type face to a printing position, and a plurality of such sectors are rotatably mounted on a shaft 17. Each sector 14 is biased by a spring 18 to rotate in one direction, and is provided with a pinion 15 in meshing engagement with the pinion 13 of the type wheel 11, and is also provided with a number selecting ratchet 16 for the selection of number type faces of l 9 and 0.

Reference numeral 19 designates an operation bar to rotationally drive the sectors 14 all at once, and bar 19 is adapted to make an arcuate reciprocal motion over a predetermined angular range about the shaft 17. Reference numeral 20 designates a selection member having a pawl 21 formed at one end for engagement with the number selecting ratchet 16 and pivotally mounted on a shaft 22 at the other end thereof.

The selection member 20 is held in engagement with an end of the armature 26 of an electromagnet 24 under the biasing force of a spring 23, which armature 26 is pivotally mounted on a shaft 27. Reference numeral 28 designates a spring and 29 designates a stopper.

Reference numeral 30 designates a hammer, 31 an ink ribbon, and 32 a paper roll.

With the arrangement described, when data obtained by the operation of an electronic computer is impressed on the coil 25 of the electromagnet as an electric signal, the armature 26 is attracted by the electromagnet 24, causing the selection member 20 to movein the direction of the arrow 34, so that the pawl 21 is brought into engagement with the number selecting ratchet 16 to stop the rotation of the sector 14 and thereby to select a number desired to be typed. Then, the hammer 30 is operated in the direction of the arrow 35 and the number is typed on the rolled paper 32. This type of printing apparatus is known in the art.

FIG. 2 and onward show an embodiment of the present invention, in which FIGS. 2, 3, 4a and 4b show a suitable electromagnetic control device for supplying a driving force to the high speed printing apparatus of the invention as well as the entire construction of the high speed printing apparatus.

Reference numeral 41 designates an A.C. or DC. motor of a power sufficient to operate the printing apparatus.

The motor 41 rotates a gear 42 connected to the motor shaft and the gear 42 rotates a clutch gear 43 in meshing engagement therewith. The clutch gear 43 has a clutch ratchet wheel 45 secured thereto by suitable means. A clutch disc 44 has a belt wheel 46 fixed thereto and also has a clutch lever 49 connected thereto by suitable means. The lever 49 is provided with a pawl 49a for engagement with the clutch ratchet wheel 45.

A trigger lever 47 is provided as the armature of an electromagnet 48, and is formed with a pawl 47a for engagement with the clutch lever 49. The clutch lever 49 also serves to operate an on-off switch 50 for the motor 41.

- mounted on the shaft 54 thereof. On the shaft 54 is also mounted a print cam 55 which is in abutting engagement with a print lever 56.

A wheel shaft 57 is supported on side frames 58 by suitable means and has a wheel gear 59, a distribution plate 60 and a pair or clear cams 61 fixedly mounted thereon. It also has a plurality of type wheels 62 rotatably mounted thereon.

A detector coil 63 is connected to the side frame 58 by suitable means in opposed relation to the distribution plate 60.

The print lever 56 is rotatably mounted on a shaft 64 supported by the side frames 58, with one end butting against the print cam 55 and the other end connected to a platen 65 by suitable means. A spring 66 has one end anchored to the print lever 65, with the other end anchored to a pin 67 fixedly provided on the side frame 58. Ribbon spools 69 are supported by a ribbon holder 70 by suitable means, with an ink ribbon 71 wound thereon. The mechanism by which the print lever 56 and the platen 65 are engaged with each other may be of the type shown in FIG. 4b.

Namely, referring to FIG. 4b, a print lever 56' and a platen lever 101 are rotatably mounted on a shaft 64 which is supported by the side frames 58, and a spring 102 is extended between an end 56a of the print lever 56 and an end 1010 of the platen lever 101. With the spring 102 thus disposed, the end 56'b of the print lever 56' and the end l01b of the platen lever 101 clamp a platen shaft 65a therebetween, and the platen 65 can be mounted and demounted in the direction of the arrow.

Inwardly of the ribbon pools 69 are provided a pair of ribbon detector levers '72 for issuing a reversing instruction to each ribbon spool upon detectingthe terminal end of the ribbon, said ribbon detector levers being mounted on the ribbon holder 70.

The side frames 58 further have a plurality of type selecting electromagnets 73 and a paper roll 74 mounted thereon by suitable means.

The construction of the mechanism shown in FIG. 2 will bedescribed-in-further detail with reference to FIGS. 3, 4a and 4b hereunder:

The clear cam '61 has an operation bar 75 fixed thereto, which extends througha slot 62q formed in each of the typewheels 62 andmakes a circular motion about the wheel shaft 57. Alternatively, the clear cam 61 and the operation bar 75 maybe engaged with each other, as shown in FIG. 4b, by providing an operation bar guiding slot 61'a in a clear cam 61 and connecting an end 75a of the operationbar 75 to said clear cam 61' with a buffer spring 100 interposed therebetween. Each of the type wheels 62isprovided with type faces 62b, a ratchet 62c and a bearing 62d, and the inner end of ahelicalspring 76 is 'secured'to the bearing 62d, the outer endof said helical'spring being anchored to the operation bar75.

A pair of selection clear levers 77 are pivotably mounted on a selection lever shaft 78 at the opposite ends thereof. Each of the selection clear levers 77 has one end fixed to a selection clear bar 79 in opposed relation to the clear cam 61, with the other end being operativelyconnected to a bar 81 through a spring 80. The selection lever shaft 78 an the selection clear bar 79.are arranged in parallel relation to the type wheel shaft 57. I

A plurality of selection members 82, are pivotably mounted side-by-side on the selection lever shaft 78 in opposed relation to the type wheels 62 respectively. Each of the selection members 82 has a pawl 82a formed at a portion thereof for engagement with the ratchet 62c of the associated type wheel 62 to hold said type wheel against rotation upon selection of a type face 62b'to be denoted. Further, each of the selection members 82 is biased in one direction by a spring 83, with one end in engagement with a reversion lever 84 and the other end in abutment against a stopper 85.

The reversion lever 84, by which the selection member 82 is operated, is pivotably mounted on a shaft 86 with one end in engagement with said selection member 82 and the other end in engagement with a reversion spring 87. The reversion spring 87 causes a snap action of the reversion lever 84. Namely, the reversion spring 87 normally urges the reversion lever 84 to rotate in a clockwise direction in the stationary state but, when'the end of the reversion lever 84 moves beyond the dead point of the reversion spring 87, it is snapped in an opposite direction by the biasing force of said reversion spring and self-retained in said position.

Below the reversion levers 84 are provided a plurali ty of electromagnets 73 for operating the respective reversion levers, arranged in side-by-side relation. The

- electromagnets 73, one for each type wheel 62, are fixedly mounted in staggered relation on a magnet mountribbon holder 70.

ing plate 89 by suitable means, and each has an armature 90. The armature 90 has one end biased by a spring 91, with the other end 90a in engagement with a pusher pin 92. Further, the armature 90 is an abutting engagement at its rear end portion with a projection 93a or 93b formed on an armature stopper plate 93. The upper end 92a of the pusher pin 92 is stepped and extends upwardly through a guide hole 89d formed in the magnet mounting plate 89 to abut against the reversion lever 84, while the lower end 92b thereof is in engagement with the armature 90 and extends downwardly through guide hole 930 in the armature stopper plate 93. j

Next, the ribbon feeding mechanism will be described with referenceto FIG. 9. A ribbon holder 70 is provided with ribbon spool shafts 1 10, and a ribbon lever shaft 114, and ribbon wheels 111, 111' are mounted on said ribbon spool shafts 110, 110' respectively. The directions of the teethof the ribbon wheels 1-11, 111 are opposite to each other and these ribbon wheels are pressed against the ribbon holder 70 by spring seats 112, 112' respectively. On ribbon lever shaft l14'is rotatably-mounted a ribbon lever 113. The ribbon lever 113 is urged to rotate in a clockwise direction by a ribbon lever spring 124 which extends between the ribbon lever 113 and a portion 70a of the A reverse rotation preventing lever 115 for the ribbon wheels 111, 111' is rotatably mounted on a pm provided on the ribbon holder 70, and an antireverse switch spring 120 is extended between the ribbon holder 70 and an end 115a of the reverse rotation preventing lever 115, thereby to urge said reverse rotation preventing lever 115 in a horizontal direction. The ribbon lever l 13 is provided with a pin 113 on which a reverse lever 116 and a ribbon feed claw 117 are rotatably mounted.

Two ribbon detecting levers 72, 72 are rotatably mounted on a ribbon detecting pin 1 18 provided on the ribbon holder 70. The ribbon detecting lever 72 has detecting arms 72a, 72'a provided with adetecting element 119 or 119' (the detecting element 119' being not shown). These detecting elements 119, 1-19' are pressed against the ink ribbon 71 by a ribbon detecting spring 122 mounted on the pin 118. I

Between the reverse lever 116 and the ribbons lever 113 is extended a spring 121 which urges said reverse lever 116 in a horizontal direction. The ribbon lever 113 is in engagement with the ribbon feeding lever 123 and said ribbon feeding lever 123 imparts an oscillation to the ribbon lever 113 incident to movement of the print cam 55.

Next, the paper feeding mechanism will be described with reference to FIG. 10.

A paper housing 152 and a paper guide 153 are formed by plates 150, 151 connected to the side frames 58. The plate is provided at a portion thereof with notches 154, 154', through which portions of rubber rollers 155, 155' extend into said paper housing 152. A paper 74 is supported by the rubber rollers 155, 155' and an end 151a of the plate 151.

The rubber rollers 155, 155' are fixedly mounted on a shaft 156 which is rotatably supported by the side frames 58. The shaft 156 also has a pulley 157 fixedly connected to one end thereof.

The plate 151 is formed at a potion thereof with a through-hole 158, through which a paper feeding rubber roller 160, fixedly mounted on a paper feeding shaft 159, extends into the paper guide 153. Reference numeral 161 designates a press roller rotatably mounted on a pin 163 provided on a press roller receiving member 162. The press roller receiving member 162 is rotatably mounted on a pin 164 and biased by a spring 165 anchored to one end thereof, whereby said press roller 161 is pressed against the paper feeding rubber roller 160. Reference numeral 165 designates a pressure releasing lever which has a pin 166 fixed to a portion thereof in confronting relation with the press roller receiving member 162.

a paper cutter lever 168 carrying a paper cutter 167 thereon is adapted to be rotatable upwardly through a predetermined angle and, when said paper cutter lever 168 is rotated upwardly (into a position indicated by the phantom line), it depresses the pressure releasing lever 165 and simultaneously causes the press roller receiving member 162 to rotate in a clockwise direction against the biasing force of the spring 165 by the pin 166, whereby the press roller 161 is released from pressure engagement with the paper feeding rubber roller 160.

A driving plate 169 fixed to the shaft 54, and a star wheel 171 fixed to the paper feeding shaft 159, are an intermittent driving mechanism well known in the art. The driving plate 169 has a pin 170 fixed thereon, which is received in a slit 171a formed in the star wheel 171, to drive the start wheel. In the embodiment shown, four such slits 171a are formed in the star wheel 171,50 that the starwheel 171 is rotated a quarter of its revolution upon completion of one revolution of the driving plate 169. The star wheel 171 is also provided with a pulley 172, and a crossing belt 173 is engaged around said pulley 172 and the aforesaid pulley 157.

Now an unnecessary zero eliminating mechanism will be described with reference to FIGS. 5, 6, 7 and 8 hereunder:

The selection members 82 are each provided with the pawl 82a at a portion thereof for engagement with the ratchet 62c, 62c as stated previously. This selection member 82 has a hook 82b formed at one end thereof for engagement with the corresponding one of a plurality of selection member discrimination levers 94 pivotally mounted on a discrimination shaft 95. Each of V the selection member discrimination levers 94 has an engaging portion 94a for number printing and a bent lug 94b at one end thereof, and is held in abutting engagement with a discrimination clear bar 97 under the biasing force of a spring 96, with said bent lug 94b engaging an upright portion 94c at the top end of the adjacent discrimination lever 94 for the next lower digit position. A discrimination clear lever 98 has one end pivotably mounted on the discrimination shaft 95, with the other end fastly connected to one end of the discrimination clear bar 97. The discrimination clear bar 97 is in contact with a pair of discrimination cams 99 provided coaxially with the print cam 55 inside of the respective side frames 58, to be operated by said discrimination cams as the latter rotate, and thereby rocks the selection member discrimination levers 94 against the biasing force of springs 96 respectively. The type wheel 62 is provided with type faces for numbers and decimal point at a portion 62b, and the notch 62c for decimal point is made deeper than the other notches for numbers.

FIGS. 7 and 8 show another form of the unnecessary zero eliminating mechanism, wherein a specific number of the plurality of type wheels are provided with a type face of decimal point only, unlike the type wheels of FIG. 5 which have both the type faces for numbers and the type face for decimal point thereon. Accordingly, selection members 82A for decimal point and selection members 82B for numbers are provided, instead of the selection members 82 in FIG. 5, for operation with type wheels 62A for decimal point and type wheels 62B for numbers respectively. The other portions of the mechanism are constructed in the same manner as in FIG. 5.

OPERATION The operation of the high speed printing apparatus of the invention constructed as described above will be explained with reference to FIGS. 2 4.

In recording data produced, for example, by a computer, a printing instruction key (not shown) of the printing apparatus is depressed, whereupon the electromagnet 48 is energized. Therefore, the trigger lever 47. is retracted by the electromagnet 48 to turn the motor driving switch 50 on, and at the same time the pawl 47a of the trigger lever 47 is disengaged from the clutch lever 49 and the pawl 49a of said clutch lever 49 is brought into engagement with the clutch ratchet wheel 45. The rotation of the motor 41 is transmitted to the belt wheel 46 through he motor gear 42 and the clutch gear 43 and thence to the second belt wheel 51 through the belt 52.

Incident thereto, the wheel gear 59 and the clear earns 61, which are fixed on the wheel shaft 57, are rotated through the intermediate gear 53 and, therefore, the operation bar fixed to said clear cams 61 is also rotated. The operation bar 75 has one end of each of the helical springs 76 disposed in the respective type wheels 62 anchored thereto and further is in engagement with an end 62a of the slots 62a of the respective type wheels 62 which are biased by said helical springs 76 respectively. Thus, it will be seen that the type wheels 62 are rotated in a clockwise direction all at once incident to rotation of the operation bar 75. The distribution plate 60 and detector coil 63 cooperate to detect, synchronously with the rotation of said type wheels 62, the type faces 62b of the respective type wheels which are in the printing position, and compare the same with the information memorized in a separate memory device and drive only those electromagnets 73 which are associated with the digit positions for which said type faces and said information conform to each other.

When an electromagnet 73 is energized, the associated armature is attracted to cause one end of the reversion .lever 84 to pivot clockwise against the biasing force of the spring 87. As soon as the end of the reversion lever 84 passes the dead point of the spring 87, it is sprung by the snapping action of said spring and held in its position even after the armature 90 returns to its original position upon interruption of the current passing through the electromagnet 73. As the reversion lever 84 is shifted in the manner described, the selection member 82 in engagement with the other end of said .reversion lever is caused to pivot in a counterclockwise direction by said reversion lever and the pawl 82a thereof is brought into engagement with the ratchet 62c of the type wheel 62, holding said type wheel 62 against rotation and thus placing the type face to be recorded in the printing position.

In this case, the operation bar 75 continues to rotate within the slot 62a, carrying one end of each helical spring 76 anchored thereto, even after the type wheel 62 is held against rotation, so that said helical spring 76 is wound up, with the amount of deflection'increasing, and hence a large rotational force is stored in the type wheel 62.-After the type faces to be recorded, of the type wheels 62, have all been selectively placed and held stationary in the printing position in the manner described, the platen 65 fixedly mounted on the print levers 56 is pressed against the type wheels 62 by the action of the print cams55, hereby the type faces are printed on'thepaper. 1 I 6 Upon completion of the printing, the lobes 61a of the respective clear earns 61 cause the selection clear levers 17-7 to rotate in a clockwise direction to lower the clear bar 79- in engagement with the undersurfaces of said clear levers 77,w hereby the selection members 82 are depressed all at once and the reversion levers 84for the respective selectionmembers are caused to pivot in a counterclockwise to their original positions past the dead point of the associated springs 87. At the same time, the selection members 82 are released from engagement with the respective type wheels 62, liberating saiditype wheels. As the lobes 61a of the clear cams 61 further rotate, the selection clear levers 7'7 and the clear bar 79 are returned to their original positions by the biasing force of the springs 80 respectively.'As soon as. each type wheel 62'is liberated, it is quickly rotated a clockwise direction under the rotational force previously stored in the associated helical spring 76, until the edge 62'a of the slot 620 formed therein abuts against the continuously rotating operation bar 75. Thereafter, the type wheel 62 rotates following the rotating operation bar 75. ln this case, according to FIG 4, the type wheel 62 is brought into contact with the op'erationbar75 with shock but, since the clear cam 61' and the operation bar 75 are engaged with each other by means of the buffer spring 100, the operation bar 75 rnoves along the slot 61'a formed in the clear cam 61 and absorbs the shock while winding said buffer spring 100.

Since the arrangement is made, by providing a clutch, such that the wheel shaft 57 stops rotating upon completion of one full turn, the operation bar 75 is also stopped at its original position after making one revolution and by this step one cycle of printing operation is completed.

According to the invention, as described above, the helical spring 76 is mounted in each of the type wheels 62 to bias said type wheel, and a portion of each type wheel 62 is engaged with the operation bar 75 so that all of the type wheels may be rotated incident to rotation of said operation bar 75 simultaneously. Further, the type faces 62b are provided over a half of the circumference of the type wheel and the ratchet 620 is provided over the remaining half of the same to directly clamp said type wheel 62, so that the type faces are selected by a first half revolution of the operation bar all operation for printing can be completed by one revolution of the operation bar 75 or one revolution of the respective type wheels 62;

Although the embodiment described and illustrated above is arranged such that one cycle of printing operation is completed by one continuous revolution in one direction of the operation bar 75, it is to be understood that the arrangement may alternatively be made such that the operation bar-75 is rotationally reciprocated through a predetermined angle only to perform the selection of the type faces in its forward stroke and clearance of the same in its return stroke, i.e., one cycle of printing operation is completedby one reciprocal motion of the operation bar 75. Still alternatively, the arrangement may be made such that the type faces are provided over the entire periphery of each type wheel 62', while the ratchet 620 is formed on one side of the type wheel, and theselection of the type faces is efclearance of the same is effected by another revolution of the type wheel, i.e. 'one cycle of printing operation is completed by two successive revolutions of the type wheel 62'. Such arrangement isadvantageous in reducing the diameter of the type wheels 62.

The operation of the ribbon feeding mechanism will be explained hereunder with reference to FIG. 9. When the ribbon feeding lever 123 is moved by the print cam 55in the direction of the arrow B and the ribbon lever 113 is moved in a counterclockwise direction, from the state of FIG. 9, the ribbon feeding claw 117, pivoted to the ribbon lever 113, is also moved in the direction of the arrow B, causing the right side ribbon wheel 11] to rotate in a clockwise direction. When the right side ribbon wheel has rotated one pitch in a clockwise direction in the manner described, the reverse rotation preventing lever falls in' the next tooth to prevent the right side ribbon wheel 111 from reverse rotation, and thereafter the ribbon feeding lever 123. returns to the original position under the biasing force of the rib-- bon lever spring 124, while following the print cam 55, whereupon the state of FIG. 9 is'resumed. As the printing operation continues, the right side ribbon wheel 111 is further rotated in a clockwise direction as described above, incident to rotation of the print cam 55. The ribbon wheel 111 is provided with a projection ll 1a which is received in a hole in the underside of the ribbon spool 69. Therefore, by the rotation of the right side ribbon wheel 111, the ink ribbon 71 is would up on the right side ribbon spool 69. Thus, the ink ribbon 71 travels from the left to right and the diameter of the ink ribbon wound on the right side ribbon spool 69 becomes progressively large, whereas the diameter of the ink ribbon stored on the left side ribbon spool 69 becomesprogressively small. The detecting plate 119 is held in pressure contact with the ink ribbon 71 on the ribbon spool 69, by the ribbon detecting spring 122. Therefore, the ribbon detecting lever 72 carrying the ribbon detecting plate 119, on each side, rotates in a counterclockwise direction as the diameter of the ink ribbon varies. Below the ribbon detecting lever 72 is provided a reverse rotation instruction arm 72b extending in the same direction as the detecting arm 72a. The reverse rotation instruction arrn 72b of the right side ribbon detecting lever 72 progressively enters the locus of return movement of a claw 116a of the reverse lever l 16, which is reciprocated by the pivotal movement of the ribbon lever 113, and is finally brought into meshing engagement with the left side claw 116a of the reverse lever 116. As the ribbon lever 113 further makes its return movement in a direction opposite to the direction of the arrow B, in this condition, under the biasing force of the spring 124, the reverse lever 116 rotates in a clockwise direction. When the reverse lever 116 passes the neutral point of the spring 121, which is biasing said reverse lever 116 in a counterclockwise direction, it is conversely biased in a clockwise direction by said spring 121 and disengaged from the right side ribbon wheel 111 and brought into engagement with the left side ribbon wheel 111. Accordingly, the ribbon feeding claw 117 is urgedin a clockwise direction and its reverse rotation instruction portion 117a causes the reverse rotation preventing lever 115 to rotate in a counterclockwise direction. The reverse rotation preventing lever 115 is now urged in a counterclockwise direction by the switch spring 120 and disengaged from the right side ribbon wheel 111 and brought into meshing engagement with the left side ribbon wheel 111', similar to the ribbon feeding claw 117. Therefore, when the ribbon lever 113 is oscillated thereafter, the ink ribbon 71 is fed toward the left, opposite to the preceding case. The direction of travel of the ink ribbon is changed again when the diameter of the ink ribbon on the right side has been reduced and the reverse rotation instruction arm 72b of the right side detecting lever 72 has been brought into engagement with the right side claw 1 16a of the reverse lever 116.

The ribbon wheel spring seat 112 is provided at the center thereof with a hole 112d which is smaller in diameter than the ribbon spool shaft 110, and a hole 112a is formed in succession to said central hole 1 12d, which is large enough to provide for passage of the ribbon spool shaft 110 therethrough. On the other side of the hole 112a is formed a hole 112b, through which a projection 1110 of the ribbon wheel 111 to drive the ribbon spool 69 extends. One of the legs of the ribbon wheel spring seat 112, which extend in three directions, is provided at the tip thereof with a downwardly bent lug 1120 which is adapted to be received in a spring seat positioning hole lllb of the ribbon wheel 111. With the construction described above, when the ribbon wheel is dropped, with the ribbon spool shaft 110 standing upright on the ribbon holder 70, which is followed by mounting the ribbon wheel spring seat on the ribbon spool shaft with the latter extending through the hole 112 a of the former, passing the projection 111a of the ribbon wheel 111 through the hole 112b, rotating the ribbon wheel spring seat 112 to the right around the hole 112b while pressing said spring seat and inserting the central hole 112d into a groove formed in the ribbon spool shaft 110 at the same level as the ribbon wheel spring seat 112, the downwardly bent lug 112C falls into the positioning hole lllb and the stable condition of FIG. 9 can be obtained.

Next, the operation of the paper feeding mechanism will be explained with reference to FIG. 10. When the paper roll 74 is dropped into the paper housing 152, it is supported by the rubber rollers 155, 155' and the end belt 173, and the rubber rollers 155, 155' are also' rotated incident thereto, so that the paper roll 74 in contact with said rubber rollers 155, 155' is rotated in a clockwise direction by friction. By arranging that the clutch is maintained in the engaged position and the motor is maintained in operation while the paper feeding lever is being pressed, the paper roll 74 is continuously rotated incident to rotation of the rubber rollers 155, 155'.

When the terminal end of the rolled paper 74 reaches one end 151a of the plate 151, it is led to a position below said end 151a of the plate 151 and introduced into the paper guide 153. As the terminal end of the paper 74 is further advanced, it is caught between the paper feeding rubber roller and the press roller 161 and thereafter the paper- 74 is sent at an accurate pitch incident to rotation of the paper feeding rubber roller 160. By dropping the paper roll 74 into the housing 152 and pressing the paper feeding lever as described above, the paper 74 is-automatically fed, passed through the paper guide 153, led to near the paper cutter 167 and set in position. Thereafter, upon completion of printing of the operation result, the star wheel 171 is rotated a quarter of its revolution by the pin 170 of the driving plate 169, whereby the paper feeding rubber roller 160 is rotated and the paper is fed at an accurate pitch, incident to the rotation of said paper feeding rubber roller, because the paper is sufficiently pressed against said rubber roller by the press roller 161. When it is desired to pull off the paper, the paper cutter lever 168 is rotated upwardly (to the position shown by the phantom line), whereby the pressure releasing lever is depressed and the press roller receiving member 162 is rotated in a clockwise direction bythe pin 166, sov that the press roller 161 is disengaged from the paper feeding rubber roller 160 and the paper 74 can be pulled off simply.

Now, the operation of the unnecessary zero eliminating mechanism will be described hereunder with reference to FIGS. 5 and 6.

When the printing instruction key (not shown) is depressed, the operation bar 75 starts to rotate in a clockwise direction, and accordingly, winds up the associated helical springs 76, to make a complete turn. The electro-magnet 73 is energized to attract the armature 90, when the number type face to be printed of each type wheel 62 is selected by the type face position detectors 60, 63 (see FIG. 4a) operating in synchronism with said type wheel, whereupon each selection member 82 is caused to pivot in a counterclockwise direction by the end extremity of said armature 90, and the pawl 82a of said selection member is brought into engagement with the number selection ratchet 62c of the type wheel 62, to hold said type wheel against rotation. Thus, the desired number is selected.

selection member discrimination cams 99 are rotatedin acounter-clockwise direction so that the selection member discrimination clear bar 97 falls into the step of said discrimination earns 99 under the biasing force of the springs 96, permitting the respective selection member discrimination levers 94 to pivot clockwise.

In this case, the selection members 82 corresponding to those type wheels 62 whose type faces have already been selected are held stationary in positions slightly spaced counterclockwise from the positions of abutting engagement with the respective stoppers 85 as described above. Therefore, the hooks 94d of thediscrimination levers 94 inthe same planeassaid selection members 82, or for the same digit positions, are

held against clockwise rotation by the hooks82d of said selection members and retained in their positions.

Further, each of the selection member discrimination levers'94 constitutes a bridge to restrain the adjacent discrimination lever in'the next lower digitposition as stated previously. Therefore, the discrimination levers 94 for the lower digit positions from the highest digit position selected are also held in their positions, but the discrimination levers for the digit positions higher than said selected highest digit position make a clockwise pivotal movement following the discrimination clear bar 97 without being blocked by the selection members 82 as said selection members have not been rotated in a counterclockwisedirection, and the hooks 94a thereof are brought into confronting relation to the hooks 82c of the associated selection members 82, to prevent counterclockwise rotation of said selection members;

Similarly, where the decimal point has been selected and the pawl 82a of the pertinent selection member 82 is in engagement with the decimal point selection ratchet 62e of the corresponding type wheel 62, the inclination of said selection member 82 is greater than before, because the groove of said ratchet 62e is deeper than that of the number selection ratchet 62c, and accordingly the amount of downward movement of the hooks'82c, 82b, 82d and 82e is larger.

Consequently, the hook 82b of the selection member 82, and the side face 94e of the bent lug 94b of that selection member discriminating lever 94 which is one digit position higher than the digit position for which the decimal point has been selected, are brought into abutment against each other. Where no numbers are selected in the digit positions higher than the decimal point, the selection member discrimination levers 94 for the next higher digit position and the digit positions lower than that remain in the same conditions as before, but those for the digit positions higher than said next higher digit position from the decimal point restrain the counterclockwise pivotal movement of the associated selection members 82.

Upon completion of the above-described operation, and after the zero position or positions have been detected by the type face position detectors 60, 63 (FIG. 4a) which are synchronized with the type wheels 62,

the electromagnets 73 for all digit positions are energized all at once, whereupon the unrestrained selection members 82 are caused to pivot in a counterclockwise direction and lock the associated type wheels 62 in the zero position to select the zero type face, but the restrained selection members are held against counterclockwise pivotal movement by the associated ,discrimination levers 94 and do not select the zero type faces. In other words, the zero faces for-the decimal digit lower than the highest digit position to be printed are selected but the zero faces for the, digit positions higher than said highest digit position are not selected.

In this case, however, the selection members 82 for the digit positions for which the number type faceshave already been selected do not select the zero type faces because these selection members have already. rotated in a counterclockwise direction. Further, where the decimal point has been selected and there are no significant numbers for the digit positions higherthan that of the decimal point, the zero type faces for the next higher digit position with respectto said digit position and the digit positions lower than said next higher digit positions can be selected, but the zero type faces for the digit positions higher than said next higher digit position cannot be selected. As described above, the type faces for all digit positions are selected during the clockwise rotational movement of the operation bar 75 within the slots 62a in the respective type wheels and in this period, the platen 65 is operated to have the selected type faces printed on the paper all at once. Upon completion of the printing,each of the selection members 82 are rotated clockwise by. the lowering selection member clear bar 79, so that the associated reversion levers 84 are shifted back into the original position and the engagement with the associated type wheels 62 is released. The operation of returning the selection member discrimination clear' bar 97 to the original position is effected before the type face selecting operation. I

According to the invention, as described above, the selection members 62 and the selection member discrimination levers 94, each constituting a bridge to receive the discrimination lever of the next lower digit position, are associated with each other in restraining relation and, further,'the depths of the number selection ratchet 62c and decimal point selection ratchet 62e are varied from each other so as to produce a difference in amount of displacement of the selection member between when said selection member selects a number by engagement with the ratchet 62e and when the same selects a decimal point by engagement with the ratchet 62e. As a result, in selecting the zero type face at least, the difference in amount of displacement of the selection member 82 is discriminated and simultaneously said selection member 82 is restrained, by the selection member discrimination lever, and thus the discrimination and selection of significant zero are achieved. In other words, the arrangement is such that when a number is selected, the selection member 82 restrains the selection member discrimination lever 94 for the same digit position, whereas when a decimal point is selected, said selection member restrains the selection member discrimination lever for the next higher digit position than the digit position of said decimal point by engagement with the bent lug or bridge of said discrimination lever. Further, when there are numbers in the higher digit positions relative to the decimal point, the selection members 82 for the highest digit position of the number to be printed and the lower digit positions relative thereto are not restrained by the associated selection member discrimination levers 94 but those for the higher digit positions than said highest digit position are restrained due to the bridge structure of the respective discrimination levers. When there are no numbers in the higher digit positions relative to the decimal point, the selection members for the next higher digit position and the lower digit positions than said next higher digit position are not restrained.

The operation of the mechanism shown in FIGS. 7 and 8 is essentially similar to that of the mechanism shown in FIG. 5 and 6, and, therefore, will be explained only briefly hereinafter:

This mechanism comprises selection member discrimination levers of exactly the same construction as that of the discrimination levers described above. However, this mechanism differs from that described above in that while in the latter the associated selection members are all of the same type, each having the hooks 82c, 82d and 82b, 82e formed at two locations, in the former the selection members are divided into two types, i.e. number selection members 823 each provided with only the hooks 82c, 82d of those mentioned above and decimal point selection members 82A each provided with only the hooks 82b, 82e of the same. Moreover, while in the latter each of the type wheels 62 is provided with both the number type faces and the decimal point type face, in the former the type wheels are divided into two types, i.e. type wheels 62B each having number type faces only and type wheels 62A each having decimal point type face only, said decimal point type wheels 62A being operatively associated with said decimal point selection members 82A respectively in confronting relation each other and said number type wheels 623 being operatively associated with said number selection members 82B respectively in confronting relation with each other. In addition, while in the latter the selection of decimal point is detected by a change in figure of the selection member 82, in the former the same is detected by a motion of the decimal point selection member 82A, the manner in which said selection member co-operates with the selection member discrimination lever 94 being the same as in the preceding embodiment.

As described above, according to the mechanism shown in FIGS. 7 and 8, each selection member disbridge for operative association with the adjacent lower selection member discrimination lever, and is arranged to take two different positions, i.e. a position to restrain the associated number selection member 828 and a position not to restrain the same, so as to restrict the rotation of said number selection member 82B. Said two positions are discriminated, in the selection of zero in the final stage, by whether or not the number selection number 82B and the decimal point selection member 82A have already been rotated to select number type faces I 9 and the decimal point type face.

Namely, when the number type faces I 9 have already been selected, the number selection members 82B for the digit positions higher than the highest digit position selected by the selection member discrimination lever 94 are restrained from rotation but the number selection members for said highest digit position, and the digit position lower than that, are not restrained. Further, when there are no numbers in the digit positions higher than the decimal point, the number selection members 82B for the next higher digit position relative to said decimal point, and the digit positions lower than that, are not restrained from rotation.

As may be understood from the foregoing description, according to the present invention the selective printing of zero type face on various occasions can be attained by a very simple mechanism, once the position of decimal point has been designated, only by arranging the selection member discrimination levers, each being shiftable between two positions, side-by-side for cooperation with the respective selection members on which type faces are provided. Therefore, the apparatus of the invention is highly advantageously used as a printing apparatus for electronic desk computers which are used in most cases by previously designating the position of decimal point.

Although the present invention has been described and illustrated herein by way of a specific embodiment thereof, it is to be understood that the invention is not restricted only thereto but many changes and modifications are possible without deviating from the spirit of the invention.

What is claimed is:

l. A high speed printing apparatus comprising a plurality of type wheels arranged side by side in the longitudinal direction of a platen and rotatably mounted on a drive shaft, a plurality of helical springs, each of said type wheels having a ratchet portion and having the inner end of one of said helical springs attached thereto, each of said type wheels having a slot therein, an operation bar extending through said slots, said operation bar being attached to said drive shaft for rotation with said drive shaft, a plurality of electro magnets, a plurality of selection members arranged respectively for engagement with each of said type wheel ratchet portions and operated respectively by one of said electromagnets, each of said helical springs having its outer end attached to said operation bar to hold its associated type wheel in engagement with said operation bar under the biasing force thereof, means for rotating said drive shaft and attached operation bar to concurrently rotate the type wheels in engagement with said operation bar, and means for selectively energizing said electromagnets to bring said selection members into engagement with said ratchet portions of said type wheels thereby to hold said type wheels against rotation whereby particular type faces of said type wheels are selected for printing.

2. The high speed printing apparatus of claim 1 including a plurality of clear members positioned for engagement with each of said selection members, and a clear cam fixedly mounted on said drive shaft for selectively operating said clear members, said clear members being operative to clear said selection members from their type wheel selecting positions when said clear members are operated by said clear cams respectively.

3. The highspeed printing apparatus as defined in claim 1, wherein the valleys of the teeth in said ratchet portions corresponding to decimal points are made deeper than the valleys of the ratchet teeth corresponding to numerals whereby the amounts of displacement of said selection members, upon engagement with their associated type wheels, differs when a selection member selects a numeral for printing and when a selection member selects a decimal point for printing, a plurality of selection member discrimination levers positioned for engagement respectively with each of said selection members to forma bridge configuration wherein the selection member discrimination lever of a higher digital position may restrain the selection member discrimination lever of a lower digital position, said selection members and discrimination levers being so constructed that when a selection member engages a ratchet tooth corresponding to a numeral, said selection member may engage the associated selection member discrimination lever, whereas when said selectionmember engages a'ratchet tooth corresponding to a decimal point, said selection member may engage the selection member discrimination lever of the next higher digital position, whereby effective zeros are discriminated and printed.

4. The high speed printing apparatus of claim 3 wherein each of said type wheels includes type faces corresponding to numerals and a type face corresponding to a decimal point, the tooth, in the ratchet portion of each type wheel, corresponding to aid decimal point having a deeper valley than the teeth, in said ratchet portion, corresponding to numerals.

, 5. The high speed printing apparatus of claim 3 wherein said type wheels include type wheels having numeral type faces only and further type wheels having decimal point type faces only, the valley of the-ratchet teeth of the decimal point type wheels being made deeper than the valley of the ratchet teeth of the numeral type wheels.

6. The high speed printing apparatus of claim 1, including a plurality of reversing levers positioned for engagement respectively with each of said selection members, each of said reversing levers being operated by an electro-magnet to operate the selection members in engagement therewith.

Po-wfio UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTI I N Patent No. a 249 Dated September 12, 1972 Inventm-(s') S hohachi Nihira Yasuo Okawara, Takehisa Naicov and Mikio Moriya 1 v It iscettifi ed that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' 1 Please amend the heading to add the following:

[3O] FOREIGN APPLICATION PRIORITY DATA May 1, 1969 Ja an 33943/69 May 7', 19 9 Ja an 7 35038/69 May 28, 1969 Japan 41474/69 Signed and sealed this 24th day" of September 1974.

(SEAL) Attest:

M COY M. GIBSON JR; I c. MARSHALL D ANN V Attesting Officer Commissioner of Patents 

1. A high speed printing apparatus comprising a plurality of type wheels arranged side by side in the longitudinal direction of a platen and rotatably mounted on a drive shaft, a plurality of helical springs, each of said type wheels having a ratchet portion and having the inner end of one of said helical springs attached thereto, each of said type wheels having a slot therein, an operation bar extending through said slots, said operation bar being attached to said drive shaft for rotation with said drive shaft, a plurality of electro-magnets, a plurality of selection members arranged respectively for engagement with each of said type wheel ratchet portions and operated respectively by one of said electromagnets, each of said helical springs having its outer end attached to said operation bar to hold its associated type wheel in engagement with said operation bar under the biasing force thereof, means for rotating said drive shaft and attached operation bar to concurrently rotate the type wheels in engagement with said operation bar, and means for selectively energizing said electromagnets to bring said selection members into engagement with said ratchet portions of said type wheels thereby to hold said type wheels against rotation whereby particular type faces of said type wheels are selected for printing.
 2. The high speed printing apparatus of claim 1 including a plurality of clear members positioned for engagement with each of said selection members, and a clear cam fixedly mounted on said drive shaft for selectively operating said clear members, said clear members being operative to clear said selection members from their type wheel selecting positions when said clear members are operated by said clear cams respectively.
 3. The high speed printing apparatus as defined in claim 1, wherein the valleys of the teeth in said ratchet portions corresponding to decimal points are made deeper than the valleys of the ratchet teeth corresponding to numerals whereby the amounts of displacement of said selection members, upon engagement with their associated type wheels, differs when a selection member selects a numeral for printing and when a selection member selects a decimal point for printing, a plurality of selection member discrimination levers positioned for engagement respectively with each of said selection members to form a bridge configuration wherein the selection member discrimination lever of a higher digital position may restrain the selection member discrimination lever of a lower digital position, said selection members and discrimination levers being so constructed tHat when a selection member engages a ratchet tooth corresponding to a numeral, said selection member may engage the associated selection member discrimination lever, whereas when said selection member engages a ratchet tooth corresponding to a decimal point, said selection member may engage the selection member discrimination lever of the next higher digital position, whereby effective zeros are discriminated and printed.
 4. The high speed printing apparatus of claim 3 wherein each of said type wheels includes type faces corresponding to numerals and a type face corresponding to a decimal point, the tooth, in the ratchet portion of each type wheel, corresponding to aid decimal point having a deeper valley than the teeth, in said ratchet portion, corresponding to numerals.
 5. The high speed printing apparatus of claim 3 wherein said type wheels include type wheels having numeral type faces only and further type wheels having decimal point type faces only, the valley of the ratchet teeth of the decimal point type wheels being made deeper than the valley of the ratchet teeth of the numeral type wheels.
 6. The high speed printing apparatus of claim 1, including a plurality of reversing levers positioned for engagement respectively with each of said selection members, each of said reversing levers being operated by an electro-magnet to operate the selection members in engagement therewith. 